Solar Seeker (Major Project)

8/14/2019 Solar Seeker (Major Project)

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MAJOR PROJECT

Solar Seeker Cell

At

Mechanical Engineering DepartmentLovely Institute of Technology

Jalandhar-Ludhiana G.T Road, Phagwara., Punjab-144402

PROJECT BY: PROJECT GUIDE:

Abhishek Dogra (5081110781) Mr. Ranjeet Singh

Sukhdeep Singh (5081110835) Mechanical Department

Ekanshu Sharma (5081110798) L.I.T.

Amit Dhadwal (608114369)

BTECH (ME)

FINAL YEAR

L.I.T.


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ACKNOWLEDGEMENT

We take this opportunity to express our sincere gratitude to honorable Mr.

Ashok Mittle, President, Lovely Institutes, Phagwara for giving us the privilege toundertake this project in LIT.

We would like to thank our project guide Mr. Rajneet Singh (Lecturer,Mechanical Department, LIT) for providing us the valuable guidance and assistance

throughout our project work.

We also express our gratitude of thanks to Mr. Vishal Bhalla (Class Incharge)

for his timely assistance and co-operation with us.

We are also indebted to Mr. Ajay Sood, Mr. Gurveen Singh ( Faculty,

Mechanical Department) for their golden ideas and heartiest cooperation throughoutthe project work.

Last but not least we are grateful to one and all that had been associated with

our project work.

PROJECT MEMBERAbhishek Dogra

Sukhdeep SinghEkanshu Sharma

Amit Dhadwal


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CERTIFICATE

This is to be certify that this major project entitled Solar Seeker Cell in Mechanical

Engineering Department, Lovely Institute of Technology, Jalandhar-Ludhiana G.T

Road, Phagwara., Punjab-144402 is submitted by Abhishek Dogra, Sukhdeep

Singh, Ekanshu Sharma & Amit Dhadwal student of B.TECH (Mechanical

Engineering) at Lovely Institute of Technology, Phagwara (Punjab).

I further certify that this work is a original work done by them.

This work has been completed under my supervision and guidance.

I wish them all success in life.

Date: 2009-05-08 Mr. Ranjeet Singh

Place: LIT, Phagwara Faculty

LIT, Phagwara


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PROJECT DIRECTIVE

Title: Solar Seeking Cell

Team:Abhishek Dogra (5081110781)

Amit Dhadwal (608114369)

Sukhdeep Singh (5081110835)

Ekanshu Sharma (5081110798)

Objective/ Aim: To make a solar seeking cell. The device will have sunlightsensors which will sense the sun and hence move the solar cell towards the sun.

Technical details:

A solar cell converts solar energy into electricity by the photovoltaic effect.

Photons in sunlight hit the solar panel and are absorbed by semi conductingmaterials, such as silicon.

Electrons (negatively charged) are knocked loose from their atoms, allowing

them to flow through the material to produce electricity. Due to the special

composition of solar cells, the electrons are only allowed to move in a single

direction. The complementary positive charges that are also created (likebubbles) are called holes and flow in the direction opposite of the electrons in a

silicon solar panel.

An array of solar cells converts solar energy into a usable amount of directcurrent (DC) electricity.

Innovativeness & Usefulness:

1) Most commercially available solar cells are capable of producing electricity for

at least twenty years without a significant decrease in efficiency.

2) The seeker will increase the production rate of solar cell.

3) This device will be highly useful for the automobiles because of theirmovements in various directions.


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Instructions are written in the assembly code under the instruction set of the 8051

controller. After assemble the software, assembler shows a 0 error and at the same

time assembler convert this code into hex code. This hex code is now transferring into

blank IC with the help of serial port programmer.

We use serial port programmer kit to transfer the data from the computer to the blank

IC. Lot of kits are available in the market, here we use FRONTLINE KIT.


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With the help of this kit we program the IC. We use this IC for the project purpose.

When platform rotate then, platform changes its direction with the help of the

magnetic proximity sensor. Here we use reed switch to monitor the platform. Reed

switch is a special switch, sense the magnetic field. One magnet is mounting on the

base of the platform. When platform rotate then magnet influence the reed switch.

When sensor influenced by the magnet then sensor plated join together and at the

same time sensor is activate and sensor provide a signal to the controller. Controller

instant changes the direction of the motor from clock wise to anti clock wise direction.

On the end of anti clock wise position we mount one more sensor; with the help of

this sensor we again change the direction of the motor.

One LDR / photodiode is mounted on the top of platform to sense a maximum light.

When sensor sense a maximum light then resistance of photodiode become very low

and, we provide a 0 signal to the micro controller to stop the motor where it is. Now

motor is stop, until photodiode sense a maximum light. When photodiode is in darkthen again platform rotate and search a maximum light.


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BASIC NOTES ON THE CONTROLLER.

HERE WE SHOW THE NOTES ON 8051 CONTROLLER. Note that 8051 and 2051

is same, only difference is pins . In 89c2051 there are 20 pins are available and in

89c51 40 pins are available.

WELCOME TO THE WORLD OF THE MICROCONTROLLERS.

Look around. Notice the smart intelligent systems? Be it the T.V, washing

machines, video games, telephones, automobiles, aero planes, power systems, or any

application having a LED or a LCD as a user interface, the control is likely to be in

the hands of a micro controller!

Measure and control, thats where the micro controller is at its best.

Micro controllers are here to stay. Going by the current trend, it is obvious that microcontrollers will be playing bigger and bigger roles in the different activities of our

lives.

These embedded chips are very small, but are designed to replace components much

bigger and bulky In size. They process information very intelligently and efficiently.

They sense the environment around them. The signals they gather are tuned into

digital data that streams through tributaries of circuit lines at the speed of light. Inside

the microprocessor collates and calculators. The software has middling intelligence.

Then in a split second, the processed streams are shoved out.


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8051 micro controller

The 8051 developed and launched in the early 80`s, is one of the most popular micro

controller in use today. It has a reasonably large amount of built in ROM and RAM.

In addition it has the ability to access external memory.

The generic term `8x51` is used to define the device. The value of x defining the kind

of ROM, i.e. x=0, indicates none, x=3, indicates mask ROM, x=7, indicates EPROM

and x=9 indicates EEPROM or Flash.

A note on ROM

The early 8051, namely the 8031 was designed without any ROM. This device could

run only with external memory connected to it. Subsequent developments lead to the

development of the PROM or the programmable ROM. This type had the

disadvantage of being highly unreliable.

The next in line, was the EPROM or Erasable Programmable ROM. These devices

used ultraviolet light erasable memory cells. Thus a program could be loaded, tested

and erased using ultra violet rays. A new program could then be loaded again.

An improved EPROM was the EEPROM or the electrically erasable PROM. This

does not require ultra violet rays, and memory can be cleared using circuits within the

chip itself. Finally there is the FLASH, which is an improvement over the EEPROM.

While the terms EEPROM and flash are sometimes used interchangeably, the

difference lies in the fact that flash erases the complete memory at one stroke, and not

act on the individual cells. This results in reducing the time for erasure.


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Different microcontrollers in market:

PIC One of the famous microcontrollers used in the industries. It is

based on RISC Architecture which makes the microcontroller process faster

than other microcontroller.

INTEL These are the first to manufacture microcontrollers. These

are not as sophisticated other microcontrollers but still the easiest one to learn.

Atmel Atmels AVR microcontrollers are one of the most powerful in

the embedded industry. This is the only microcontroller having 1kb of ram

even the entry stage. But it is unfortunate that in India we are unable to find this

kind of microcontroller.

Intel 8051

Intel 8051 is CISC architecture which is easy to program in assembly language and

also has a good support for High level languages.

The memory of the microcontroller can be extended up to 64k.

This microcontroller is one of the easiest microcontrollers to learn.

The 8051 microcontroller is in the field for more than 20 years. There are lots of

books and study materials are readily available for 8051.


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Derivatives

The best thing done by Intel is to give the designs of the 8051 microcontroller to

everyone. So it is not the fact that Intel is the only manufacture for the 8051 there

more than 20 manufactures, with each of minimum 20 models. Literally there are

hundreds of models of 8051 microcontroller available in market to choose. Some of

the major manufactures of 8051 are

Atmel

Philips

Dallas

Philips

The Philipss 8051 derivatives has more number of features than in any

microcontroller. The costs of the Philips microcontrollers are higher than the Atmels

which makes us to choose Atmel more often than Philips

Dallas

Dallas has made many revolutions in the semiconductor market. Dallass 8051

derivative is the fastest one in the market. It works 3 times as fast as a 8051 can

process. But we are unable to get more in India.

Atmel

These people were the one to master the flash devices. They are the cheapest

microcontroller available in the market. Atmels even introduced a 20pin variant of

8051 named 2051. The Atmels 8051 derivatives can be got in India less than 70

rupees. There are lots of cheap programmers available in India for Atmel. So it is

always good for students to stick with 8051 when you learn a new microcontroller.


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Architecture

Architecture is must to learn because before learning new machine it is necessary to

learn the capabilities of the machine. This is some thing like before learning about the

car you cannot become a good driver. The architecture of the 8051 is given below.


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The 8051 doesnt have any special feature than other microcontroller. The only

feature is that it is easy to learn. Architecture makes us to know about the hardware

features of the microcontroller. The features of the 8051 are

4K Bytes of Flash Memory

128 x 8-Bit Internal RAM

Fully Static Operation: 1 MHz to 24 MHz

32 Programmable I/O Lines

Two 16-Bit Timer/Counters

Six Interrupt Sources (5 Vectored)

Programmable Serial Channel

Low Power Idle and Power Down Modes

The 8051 has a 8-Bit CPU that means it is able to process 8 bit of data at a time. 8051

has 235 instructions.


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H bridge circuit

Here we use H bridge circuit to control the direction of the motor. H Bridge is a

combination of the four transistors. Out of these four transistors two transistors is

NPN and two transistors is PNP transistor. At a time only two transistor work to run

a motor. To control the direction of motor, we use microcontroller circuit.

H Bridge is connecting with the microcontroller with the help of the optocouplercircuit. We use two optocoupler to provide a electrical isolation between motor circuit

and microcontroller circuit. We use optocoupler to provide an electrical isolation

between motor+ h bridge circuit and microcontroller circuit.


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Microcontroller circuit work on 5 volt dc, but H bridge circuit work on the 9 volt dc.In future if we change the motor then we change the supply also, If we change supply

of the H bridge circuit then there is no effect on the main processor circuit.

We use 7805 regulator circuit to provide a 5 volt dc supply to pin no 20 of thecontroller. Pin no 4 and 5 is connected to the external crystal to provide a clock pulse

to the controller. Pin no 1 is the reset pin of the controller. On this pin we connect one

capacitor and resistor circuit to provide a auto reset facility. Two ports are available

for controlling all the inputs and output. Port p3 and port P1 is available for the inputand output. The entire input signal is provided on the port p3 and motor is connected

to the port p1. Port p1.0 and port p1.1 is connected to the motor through optocouplercircuit and H bridge circuit. Light sensor and two reed sensor is connected to the port

p3.0, p3.1, p3.2.


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DC MOTOR

Here in this project we use slow speed dc motor with gear box to reduce the speed of

the platform. This type of gear motor is getting from the second hand machine.

Supply voltage of this dc motor is 6 to 9 volt dc. As we vary the voltage speed is also

vary. Current consumption of dc motor is 200 ma. It is also possible to use a stepper

motor. If we use stepper motor then we require a high current supply. Normal stepper

motor require a minimum 1 A power supply.

SPECIFICATION OF DC MOTOR USED:

MOTOR DC

MIN MAX

Size diameter 2 inch

length 2 inch

SPEED 0 RPM 100 RPM

VOLTAGE 10v 20v

Gear Assembly- Rack and Pinion


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Gears :

A gear is a component within a transmission device that transmits rotational force to

another gear or device. A gear is different from apulley in that a gear is a round wheelwhich has linkages ("teeth" or "cogs") that mesh with other gear teeth, allowing force

to be fully transferred without slippage. Depending on their construction and

arrangement, geared devices can transmit forces at different speeds, torques, or in a

different direction, from the power source. Gears are a very useful simple machine.

The most common situation is for a gear to mesh with another gear, but a gear can

mesh with any device having compatible teeth, such as linear moving racks. A gear's

most important feature is that gears of unequal sizes (diameters) can be combined to

produce a mechanical advantage, so that the rotational speed and torque of the second

gear are different from that of the first. In the context of a particular machine, the term

"gear" also refers to one particular arrangement of gears among other arrangements

(such as "first gear"). Such arrangements are often given as a ratio, using the number

of teeth or gear diameter as units. The term "gear" is also used in non-geared devices

which perform equivalent tasks:

"...broadly speaking, a gear refers to a ratio of engine shaft speed to driveshaft

speed. Although CVTs change this ratio without using a set of planetary gears,

they are still described as having low and high "gears" for the sake of
http://en.wikipedia.org/wiki/Transmission_(mechanics)http://en.wikipedia.org/wiki/Rotationhttp://en.wikipedia.org/wiki/Pulleyhttp://en.wikipedia.org/wiki/Speedhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Simple_machinehttp://en.wikipedia.org/wiki/Gear#Rack_and_pinion%23Rack_and_pinionhttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Continuously_variable_transmissionhttp://en.wikipedia.org/wiki/Rotationhttp://en.wikipedia.org/wiki/Pulleyhttp://en.wikipedia.org/wiki/Speedhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Simple_machinehttp://en.wikipedia.org/wiki/Gear#Rack_and_pinion%23Rack_and_pinionhttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Continuously_variable_transmissionhttp://en.wikipedia.org/wiki/Transmission_(mechanics)


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a circumferential component. The radial component can be ignored: it merely causes a

sideways push on the shaft and does not contribute to turning.

The circumferential component causes turning. The torque is equal to the

circumferential component of the force times radius. Thus we see that the larger gear

experiences greater torque; the smaller gear less. The torque ratio is equal to the ratio

of the radii. This is exactly the inverse of the case with the velocity ratio. Higher

torque implies lower velocity and vice versa. The fact that the torque ratio is the

inverse of the velocity ratio could also be inferred from the law of conservation of

energy. Here we have been neglecting the effect of friction on the torque ratio. The

velocity ratio is truly given by the tooth or size ratio, but friction will cause the torque

ratio to be actually somewhat less than the inverse of the velocity ratio.

In the above discussion we have made mention of the gear "radius". Since a gear is

not a proper circle but a roughened circle, it does not have a radius. However, in a pair

of meshing gears, each may be considered to have an effective radius, called the pitch

radius, the pitch radii being such that smooth wheels of those radii would produce the

same velocity ratio that the gears actually produce. The pitch radius can be considered

sort of an "average" radius of the gear, somewhere between the outside radius of the

gear and the radius at the base of the teeth.

The issue of pitch radius brings up the fact that the point on a gear tooth where it

makes contact with a tooth on the mating gear varies during the time the pair of teeth

are engaged; also the direction of force may vary. As a result, the velocity ratio (and

torque ratio) is not, actually, in general, constant, if one considers the situation in

detail, over the course of the period of engagement of a single pair of teeth. The

velocity and torque ratios given at the beginning of this section are valid only "in

bulk" -- as long-term averages; the values at some particular position of the teeth may

be different.
http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Torque


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It is in fact possible to choose tooth shapes that will result in the velocity ratio also

being absolutely constant -- in the short term as well as the long term. In good quality

gears this is usually done, since velocity ratio fluctuations cause undue vibration, and

put additional stress on the teeth, which can cause tooth breakage under heavy loads at

high speed. Constant velocity ratio may also be desirable for precision in

instrumentation gearing, clocks and watches. The involute tooth shape is one that

results in a constant velocity ratio, and is the most commonly used of such shapes

today.

Comparison with other drive mechanisms

The definite velocity ratio which results from having teeth gives gears an advantage

over other drives (such as traction drives and V-belts) in precision machines such as

watches that depend upon an exact velocity ratio. In cases where driver and follower

are in close proximity gears also have an advantage over other drives in the reduced

number of parts required; the downside is that gears are more expensive to

manufacture and their lubrication requirements may impose a higher operating cost.

The automobiletransmission allows selection between gears to give various

mechanical advantages.

Spur gears

Spur gears are the simplest, and probably most common, type of gear. Their general

form is a cylinder or disk. The teeth project radially, and with these "straight-cut

gears", the leading edges of the teeth are aligned parallel to the axis of rotation. These

gears can only mesh correctly if they are fitted to parallel axles.
http://en.wikipedia.org/wiki/Involute_gearhttp://en.wikipedia.org/wiki/Traction_(engineering)http://en.wikipedia.org/wiki/Belt_(mechanical)http://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Transmission_(mechanics)http://en.wikipedia.org/wiki/Involute_gearhttp://en.wikipedia.org/wiki/Traction_(engineering)http://en.wikipedia.org/wiki/Belt_(mechanical)http://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Transmission_(mechanics)


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Helical gears

Helicalgears offer a refinement over spur gears. The leading edges of the teeth are

not parallel to the axis of rotation, but are set at an angle. Since the gear is curved, this

angling causes the tooth shape to be a segment of a helix. The angled teeth engage

more gradually than do spur gear teeth. This causes helical gears to run more

smoothly and quietly than spur gears. Helical gears also offer the possibility of using

non-parallel shafts. A pair of helical gears can be meshed in two ways: with shafts

oriented at either the sum or the difference of the helix angles of the gears. These

configurations are referred to asparallelorcrossed, respectively. The parallel

configuration is the more mechanically sound.

In it, the helices of a pair of meshing teeth meet at a common tangent, and the contact

between the tooth surfaces will, generally, be a curve extending some distance across

their face widths. In the crossed configuration, the helices do not meet tangentially,

and only point contact is achieved between tooth surfaces. Because of the small area

of contact, crossed helical gears can only be used with light loads.

Quite commonly, helical gears come in pairs where the helix angle of one is the

negative of the helix angle of the other; such a pair might also be referred to as having

a right handed helix and a left handed helix of equal angles. If such a pair is meshed in

the 'parallel' mode, the two equal but opposite angles add to zero: the angle between

shafts is zero -- that is, the shafts are parallel. If the pair is meshed in the 'crossed'

mode, the angle between shafts will be twice the absolute value of either helix angle.

Note that 'parallel' helical gears need not have parallel shafts -- this only occurs if their

helix angles are equal but opposite. The 'parallel' in 'parallel helical gears' must refer,

if anything, to the (quasi) parallelism of the teeth, not to the shaft orientation.

As mentioned at the start of this section, helical gears operate more smoothly than do

spur gears. With parallel helical gears, each pair of teeth first make contact at a single

point at one side of the gear wheel; a moving curve of contact then grows gradually
http://en.wikipedia.org/wiki/Helixhttp://en.wikipedia.org/wiki/Helixhttp://en.wikipedia.org/wiki/Helixhttp://en.wikipedia.org/wiki/Helix


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across the tooth face. It may span the entire width of the tooth for a time. Finally, it

recedes until the teeth break contact at a single point on the opposite side of the wheel.

Thus force is taken up and released gradually. With spur gears, the situation is quite

different. When a pair of teeth meet, they immediately make line contact across their

entire width. This causes impact stress and noise. Spur gears make a characteristic

whine at high speeds and can not take as much torque as helical gears because their

teeth are receiving impact blows.

Whereas spur gears are used for low speed applications and those situations where

noise control is not a problem, the use of helical gears is indicated when the

application involves high speeds, large power transmission, or where noise abatement

is important. The speed is considered to be high when the pitch line velocity (that is,

the circumferential velocity) exceeds 5000 ft/min. A disadvantage of helical gears is a

resultant thrust along the axis of the gear, which needs to be accommodated by

appropriate thrust bearings, and a greater degree of sliding friction between the

meshing teeth, often addressed with specific additives in the lubricant.

Double helical gears

Double helical gears, invented by Andr Citron and also known as herringbone

gears, overcome the problem of axial thrust presented by 'single' helical gears by

having teeth that set in a 'V' shape. Each gear in a double helical gear can be thought

of as two standard, but mirror image, helical gears stacked. This cancels out the thrust

since each half of the gear thrusts in the opposite direction. They can be directly

interchanged with spur gears without any need for different bearings.

Where the oppositely angled teeth meet in the middle of a herringbone gear, the

alignment may be such that tooth tip meets tooth tip, or the alignment may be

staggered, so that tooth tip meets tooth trough. The latter type of alignment results in

what is known as a Wuest type herringbone gear.
http://en.wikipedia.org/wiki/Thrust_bearinghttp://en.wikipedia.org/wiki/Andr%C3%A9_Citro%C3%ABnhttp://en.wikipedia.org/wiki/Thrust_bearinghttp://en.wikipedia.org/wiki/Andr%C3%A9_Citro%C3%ABn


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With the older method of fabrication, herringbone gears had a central channel

separating the two oppositely-angled courses of teeth. This was necessary to permit

the shaving tool to run out of the groove. The development of the Sykes gear shaper

now makes it possible to have continuous teeth, with no central gap.

Bevel gears

Bevel gearused to liftfloodgate by means of central screw.

Bevel gears are essentially conically shaped, although the actual gear does not extend

all the way to the vertex (tip) of the cone that bounds it. With two bevel gears in mesh,the vertices of their two cones lie on a single point, and the shaft axes also intersect at

that point. The angle between the shafts can be anything except zero or 180 degrees.

Bevel gears with equal numbers of teeth and shaft axes at 90 degrees are called miter

gears.

The teeth of a bevel gear may be straight-cut as with spur gears, or they may be cut in

a variety of other shapes. 'Spiral bevel gears' have teeth that are both curved along

their (the tooth's) length; and set at an angle, analogously to the way helical gear teeth

are set at an angle compared to spur gear teeth. 'Zero bevel gears' have teeth which

are curved along their length, but not angled. Spiral bevel gears have the same

advantages and disadvantages relative to their straight-cut cousins as helical gears do

to spur gears. Straight bevel gears are generally used only at speeds below 5 m/s

(1000 ft/min), or, for small gears, 1000 r.p.m.

[4]

Crown gear

A crown gear or contrate gear is a particular form of bevel gear whose teeth project at

right angles to the plane of the wheel; in their orientation the teeth resemble the points

on a crown. A crown gear can only mesh accurately with another bevel gear, although

crown gears are sometimes seen meshing with spur gears. A crown gear is also

sometimes meshed with an escapement such as found in mechanical clocks.
http://en.wikipedia.org/wiki/Gear_shaperhttp://en.wikipedia.org/wiki/Bevel_gearhttp://en.wikipedia.org/wiki/Floodgatehttp://en.wikipedia.org/wiki/Floodgatehttp://en.wikipedia.org/wiki/Screw_(simple_machine)http://en.wikipedia.org/wiki/Gear#cite_note-straightbevel-3%23cite_note-straightbevel-3http://en.wikipedia.org/wiki/Gear_shaperhttp://en.wikipedia.org/wiki/Bevel_gearhttp://en.wikipedia.org/wiki/Floodgatehttp://en.wikipedia.org/wiki/Screw_(simple_machine)http://en.wikipedia.org/wiki/Gear#cite_note-straightbevel-3%23cite_note-straightbevel-3


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several turns around the helix, the worm will appear, superficially, to have more than

one tooth, but what one in fact sees is the same tooth reappearing at intervals along

the length of the worm. The usual screw nomenclature applies: a one-toothed worm is

called "single thread" or "single start"; a worm with more than one tooth is called

"multiple thread" or "multiple start".

We should note that the helix angle of a worm is not usually specified. Instead, the

lead angle, which is equal to 90 degrees minus the helix angle, is given.

In a worm-and-gear set, the worm can always drive the gear. However, if the gear

attempts to drive the worm, it may or may not succeed. Particularly if the lead angle is

small, the gear's teeth may simply lock against the worm's teeth, because the force

component circumferential to the worm is not sufficient to overcome friction.

Whether this will happen depends on a function of several parameters; however, an

approximate rule is that if the tangent of the lead angle is greater than the coefficient

of friction, the gear will not lock.[8] Worm-and-gear sets that do lock in the above

manner are called "self locking". The self locking feature can be an advantage, as for

instance when it is desired to set the position of a mechanism by turning the worm and

then have the mechanism hold that position. An example of this is the tuning

mechanism on some types of stringed instruments.

If the gear in a worm-and-gear set is an ordinary helical gear only point contact

between teeth will be achieved.[9] If medium to high power transmission is desired, the

tooth shape of the gear is modified to achieve more intimate contact with the worm

thread. A noticeable feature of most such gears is that the tooth tops are concave, so

that the gear partly envelopes the worm. A further development is to make the worm

concave (viewed from the side, perpendicular to its axis) so that it partly envelopes

the gear as well; this is called a cone-drive orHindley worm.

A right hand helical gear or right hand worm is one in which the teeth twist clockwise

as they recede from an observer looking along the axis. The designations, right hand
http://en.wikipedia.org/wiki/Gear#cite_note-wormgears3-7%23cite_note-wormgears3-7http://en.wikipedia.org/wiki/Gear#cite_note-wormgears4-8%23cite_note-wormgears4-8http://en.wikipedia.org/wiki/Gear#cite_note-wormgears3-7%23cite_note-wormgears3-7http://en.wikipedia.org/wiki/Gear#cite_note-wormgears4-8%23cite_note-wormgears4-8


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and left hand, are the same as in the long established practice for screw threads, both

external and internal. Two external helical gears operating on parallel axes must be of

opposite hand. An internal helical gear and its pinion must be of the same hand.

A left hand helical gear or left hand worm is one in which the teeth twist

counterclockwise as they recede from an observer looking along the axis.

Rack and pinion

A rack is a toothed bar or rod that can be thought of as a sector gear with an infinitely

large radius of curvature. Torque can be converted to linear force by meshing a rackwith a pinion: the pinion turns; the rack moves in a straight line. Such a mechanism is

used in automobiles to convert the rotation of the steering wheel into the left-to-right

motion of the tie rod(s). Racks also feature in the theory of gear geometry, where, for

instance, the tooth shape of an interchangeable set of gears may be specified for the

rack (infinite radius), and the tooth shapes for gears of particular actual radii then

derived from that.

External vs. internal gears

An external gear is one with the teeth formed on the outer surface of a cylinder or

cone. Conversely, an internal gear is one with the teeth formed on the inner surface of

a cylinder or cone. For bevel gears, an internal gear is one with the pitch angle

exceeding 90 degrees.
http://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Steeringhttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Steering


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Reed Sensor

The reed switch is an electrical switch operated by an applied magnetic field. It was

invented at Bell Telephone Laboratories in 1936 by W. B. Ellwood. It consists of a

pair of contacts on ferrous metal reeds in a hermetically sealed glass envelope. The

contacts may be normally open, closing when a magnetic field is present; normally

closed and opening when a magnetic field is applied; or one normally open and one

normally closed. The switch may be actuated by a coil, making a reed relay, or by

bringing a magnet near to the switch. Once the magnet is pulled away from the

switch, the reed switch will go back to its original position.

Reed switches are used in reed relays, which are used for temporarily storing

information in mid-20th Century telephone exchanges. As well, they are for electrical

circuit control, particularly in the communications field; as proximity switches for

burglar alarms and as switches in electronic pedal keyboards used by pipe organ

players and in electronic children's toys which have sound effects that need to be

activated.

Description

The reed switch contains a pair (or more) of magnetizable and electrically conductive

metal reeds which have end portions separated by a small gap when the switch is

open. The reeds are hermetically sealed in opposite ends of a tubular glass envelope.

Electromagnetic switch A magnetic field (from an electromagnet or a permanent

magnet) will cause the contacts to pull together, thus completing an electrical circuit.

The stiffness of the reeds causes them to separate, and open the circuit, when the

magnetic field ceases. Another configuration contains a non-ferrous normally-closed

contact that opens when the ferrous normally-open contact closes. Good electricalcontact is assured by plating a thin layer of precious metal over the flat contact


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portions of the reeds; low-resistivity silver is more suitable than corrosion-resistant

gold in the sealed envelope.

There are also versions of reed switches with mercury "wetted" contacts. Such

switches must be mounted in a particular orientation otherwise drops of mercury may

bridge the contacts even when not activated.

Since the contacts of the reed switch are sealed away from the atmosphere, they are

protected against atmospheric corrosion. The hermetic sealing of a reed switch make

them suitable for use in explosive atmospheres where tiny sparks from conventional

switches would constitute a hazard.

One important quality of the switch is its sensitivity, the amount of magnetic energy

necessary to actuate it. Sensitivity is measured in units of Ampere-turns,

corresponding to the current in a coil multiplied by the number of turns. Typical pull-

in sensitivities for commercial devices are in the 10 to 60 AT range.

In production, a metal reed is inserted in each end of a glass tube and the end of the

tube heated so that it seals around a shank portion on the reed. Infrared-absorbing

glass is used, so an infrared heat source can concentrate the heat in the small sealing

zone of the glass tube. The thermal coefficient of expansion of the glass material and

metal parts must be similar to prevent breaking the glass-to-metal seal. The glass used

must have a high electrical resistance and must not contain volatile components such

as lead oxide and fluorides. The leads of the switch must be handled carefully toprevent breaking the glass envelope.


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Uses

In addition to their use in reed relays, reed switches are widely used for electrical

circuit control, particularly in the communications field. Reed switches actuated by

magnets are commonly used in mechanical systems as proximity switches as well as

in door and window sensors in burglar alarm systems and tamperproofing methods;

however they can be disabled by a strong, external magnetic field. Reed switches

were formerly used in the keyboards for computer terminals, where each key had a

magnet and a reed switch actuated by depressing the key; cheaper switches are now

used. Speed sensors on bicycle wheels use a reed switch to actuate briefly each time a

magnet on the wheel passes the sensor.

Electric and electronic pedal keyboards used by pipe organ and Hammond organ

players often use reed switches to activate the notes of the keyboard. One of the

challenges with choosing switches for pedal keyboards is that since the keys are

depressed with the feet, the switch mechanism is exposed to dirt, dust, and other

particles. Reed switches are often the preferred choice because glass reed switches are

sealed, which protects them from dirt and dust. Reed switches are also widely used in

electronic children's toys which have sound effects that need to be activated when a

child uses the toy in certain ways, such as opening a toy jewellery box.

Reed relays

One or more reed switches inside a coil is a reed relay. Reed relays are used whenoperating currents are relatively low, and offer high operating speed, good

performance with very small currents which are not reliably switched by conventional

contacts, high reliability and long life. Millions of reed relays were used for

temporarily storing information in mid-20th Century telephone exchanges. The inert

atmosphere around the reed contacts ensures that oxidation will not affect the contact

resistance.


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Advantages of Reed Switches

Advantages of reed switches to the Meccano modeller are their small size, which

makes them easy to mount and unobtrusive, and the fact that the operating force

required to operate the switch is very small, thus doing away with cumbersome cams

or cranks. Reed switches, and suitable magnets, are also cheap and easily obtainable.

Disadvantages of Reed Switches

It should, however, be pointed out that reed switches do have a few disadvantages -

nothing is ever perfect!

First, the contacts and reeds are fairly small and delicate, so they won't handle large

voltages or currents which cause the reeds to spark when switched. Heavy currents

also overheat the reeds causing them to lose their springiness. If the reed contacts do

become welded together (due to trying to switch a high current) you can often freethem by sharply tapping the reed switch against a table - but not too hard or the glass

will break! It is always worth trying - you have nothing to lose because welded

contacts make the switch useless.

Maplin give typical voltage and current ratings for the switches that they supply. A

power rating, measured in Watts (W), simply means multiplying current and voltage,

but remember not to exceed the current rating - e.g., 10V at 1A = 10W, but 1V at 10A

also equals 10W, but in this case the current would be too high. If you are switching

large currents, it will be necessary to use a relay circuit with the reed switch operating

the relay coil only.


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Second, since reed switches are rather fragile, particularly if you are soldering onto

the thick lead-out wires, it's easy to break the glass and seals. If you need to bend the

lead-out wires, make sure that you grip them securely with pliers between the glass

seal and the bend point, as shown in the top of figure 2.


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Sensor

A sensor is a device that measures a physical quantity and converts it into a signal

which can be read by an observer or by an instrument. For example, a mercury

thermometer converts the measured temperature into expansion and contraction of a

liquid which can be read on a calibrated glass tube. A thermocouple converts

temperature to an output voltage which can be read by a voltmeter. For accuracy, all

sensors need to be calibrated against known standards.

Use

Sensors are used in everyday objects such as touch-sensitive elevator buttons and

lamps which dim or brighten by touching the base. There are also innumerable

applications for sensors of which most people are never aware. Applications include

cars, machines, aerospace, medicine, manufacturing and robotics.

A sensor's sensitivity indicates how much the sensor's output changes when the

measured quantity changes. For instance, if the mercury in a thermometer moves 1 cm

when the temperature changes by 1 C, the sensitivity is 1 cm/C. Sensors that

measure very small changes must have very high sensitivities. Sensors also have an

impact on what they measure; for instance, a room temperature thermometer inserted

into a hot cup of liquid cools the liquid while the liquid heats the thermometer.

Sensors need to be designed to have a small effect on what is measured, making the

sensor smaller often improves this and may introduce other advantages. Technological

progress allows more and more sensors to be manufactured on a microscopic scale as

microsensors using MEMS technology. In most cases, a microsensor reaches a

significantly higher speed and sensitivity compared with macroscopic approaches.


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Classification of measurement errors

A good sensor obeys the following rules:

Is sensitive to the measured property

Is insensitive to any other property

Does not influence the measured property

Ideal sensors are designed to be linear. The output signal of such a sensor is linearly

proportional to the value of the measured property. The sensitivity is then defined as

the ratio between output signal and measured property. For example, if a sensor

measures temperature and has a voltage output, the sensitivity is a constant with the

unit [V/K]; this sensor is linear because the ratio is constant at all points of

measurement.

Sensor deviations

If the sensor is not ideal, several types of deviations can be observed:

The sensitivity may in practice differ from the value specified. This is called a

sensitivity error, but the sensor is still linear.

Since the range of the output signal is always limited, the output signal will eventually

reach a minimum or maximum when the measured property exceeds the limits. The

full scale range defines the maximum and minimum values of the measured property.

If the output signal is not zero when the measured property is zero, the sensor has an

offset or bias. This is defined as the output of the sensor at zero input.


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If the sensitivity is not constant over the range of the sensor, this is called

nonlinearity. Usually this is defined by the amount the output differs from ideal

behavior over the full range of the sensor, often noted as a percentage of the full

range.

If the deviation is caused by a rapid change of the measured property over time, there

is a dynamic error. Often, this behaviour is described with a bode plot showing

sensitivity error and phase shift as function of the frequency of a periodic input signal.

If the output signal slowly changes independent of the measured property, this is

defined as drift.

Long term drift usually indicates a slow degradation of sensor properties over a long

period of time.

Noise is a random deviation of the signal that varies in time.

Hysteresis is an error caused by when the measured property reverses direction, butthere is some finite lag in time for the sensor to respond, creating a different offset

error in one direction than in the other.

If the sensor has a digital output, the output is essentially an approximation of the

measured property. The approximation error is also called digitization error.

If the signal is monitored digitally, limitation of the sampling frequency also can

cause a dynamic error.

The sensor may to some extent be sensitive to properties other than the property being

measured. For example, most sensors are influenced by the temperature of their

environment.

All these deviations can be classified as systematic errors or random errors.

Systematic errors can sometimes be compensated for by means of some kind of


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calibration strategy. Noise is a random error that can be reduced by signal processing,

such as filtering, usually at the expense of the dynamic behaviour of the sensor.

Resolution

The resolution of a sensor is the smallest change it can detect in the quantity that it is

measuring. Often in a digital display, the least significant digit will fluctuate,

indicating that changes of that magnitude are only just resolved. The resolution is

related to the precision with which the measurement is made. For example, a scanning

tunneling probe (a fine tip near a surface collects an electron tunnelling current) can

resolve atoms and molecules.

Types

Biological sensors

All living organisms contain biological sensors with functions similar to those of the

mechanical devices described. Most of these are specialized cells that are sensitive to:

Light, motion, temperature, magnetic fields, gravity, humidity, vibration, pressure,

electrical fields, sound, and other physical aspects of the external environment

Physical aspects of the internal environment, such as stretch, motion of the organism,

and position of appendages (proprioception)

Environmental molecules, including toxins, nutrients, and pheromones

Estimation of biomolecules interaction and some kinetics parameters

Internal metabolic milieu, such as glucose level, oxygen level, or osmolality

Internal signal molecules, such as hormones, neurotransmitters, and cytokines


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Differences between proteins of the organism itself and of the environment or alien

creatures

Artificial sensors that mimic biological sensors by using a biological sensitive

component, are called biosensors.

Photoelectric sensor

A photoelectric sensor, or photoeye, is a device used to detect the presence of an

object by using a light transmitter, often infrared, and a photoelectric receiver. They

are used extensively in industrial manufacturing. There are three different functionaltypes, opposed (a.k.a. through beam), retroreflective, and proximity-sensing (a.k.a.

diffused).

An opposed (through beam) arrangement consists of a receiver located within the line-

of-sight of the transmitter. In this mode, an object is detected when the light beam is

blocked from getting to the receiver from the transmitter.

A retroreflective arrangement places the transmitter and receiver at the same location

and uses a reflector to bounce the light beam back from the transmitter to the receiver.

An object is sensed when the beam is interrupted and fails to reach the receiver.

A proximity-sensing (diffused) arrangement is one in which the transmitted radiation

must reflect off of the object in order to reach the receiver. In this mode, an object is

detected when the receiver sees the transmitted source rather than when it fails to see

it.


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Photosensor

A photosensor is an electronic component that detects the presence of visible light,

infrared transmission (IR), and/or ultraviolet (UV) energy. Most photosensors consist

of semiconductor having a property called photoconductivity , in which the electrical

conductance varies depending on the intensity of radiation striking the material.

The most common types of photosensor are the photodiode, the bipolar

phototransistor, and the photoFET (photosensitive field-effect transistor). These

devices are essentially the same as the ordinary diode , bipolar transistor , and field-

effect transistor , except that the packages have transparent windows that allow

radiant energy to reach the junctions between the semiconductor materials inside.

Bipolar and field-effect phototransistors provide amplification in addition to their

sensing capabilities.

Photosensors are used in a great variety of electronic devices, circuits, and systems,

including:

fiber optic systems

optical scanners

wireless LAN

automatic lighting controls

machine vision systems

electric eyes

optical disk drives


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With a photodiode as the detector, the output current is proportional to the amount of

incident light supplied by the emitter. The diode can be used in a photovoltaic mode

or a photoconductive mode. In photovoltaic mode, the diode acts like a current source

in parallel with a forward-biased diode. The output current and voltage are dependent

on the load impedance and light intensity. In photoconductive mode, the diode is

connected to a supply voltage, and the magnitude of the current conducted is directly

proportional to the intensity of light. This optocoupler type is significantly faster than

one with photo transistor however transmission ratio is very low. Because of that it is

common to integrate amplifier circuit in same package.

The optical path may be air or a dielectric waveguide. When high noise immunity is

required optical conductive shield may be integrated into optical path. The

transmitting and receiving elements of an optical isolator may be contained within a

single compact module, for mounting, for example, on a circuit board; in this case, the

module is often called an optoisolator or opto-isolator. The photosensor may be a

photocell, phototransistor, or an optically triggered SCR or TRIAC. Occasionally, this

device will in turn operate a power relay or contactor.

For analog isolation, special "analog" optoisolators are used. These devices have two

independent, closely matched phototransistors, one of which is typically used to

linearize the response using negative feedback.

Application

A simple circuit with an opto-isolator. When switch S1 is closed, LED D1 lights,

which triggers phototransistor Q1, which pulls the output pin low. This circuit, thus,

acts as a NOT gate.Among other applications, opto-isolators can help cut down on

ground loops, block voltage spikes, and provide electrical isolation.


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Most common application is for switched-mode power supplies. They utilise

optocouplers for mains isolation. Because of noisy environment optocouplers with

low transmission ratio are preferred.

One of the requirements of the MIDI (Musical Instrument Digital Interface) standard

is that input connections be opto-isolated.

They are used to isolate low-current control or signal circuitry from transients

generated or transmitted by power supply and high-current control circuits. The latter

are used within motor and machine control function blocks.


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Applications of Solar seeker Cell

Solar powered automobile

Inhouse Solar cells

Soler water heaters

Solar powered flying machines

Solar powered street lights

Solar electric plants


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CONCLUSION

At last we would say that we learnt many things during our major project. We got to know about

renewable sources of energy & the urgent need of improving the solar cell industry to meet future

energy needs. Solar energy has the potential to supply all energy needs but it is diffuse, cyclic and

often undependable. It needs systems that gather and concentrate solar energy, Solar thermal &

Photovoltaic.

Hence, whatever knowledge we have gained during major project here will be an assent for

our future and we are very much thankful for the co-operation of all faculty & our classmates who

helped to complete our project.

Abhishek Dogra

Sukhdeep Singh

Ekanshu Sharma

Amit Dhadwal


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TABLE OF CONTENT

Sr. NO. CONTENT

1. INTRODUCTION

2. MICROCONTROLLER

3. H BRIDGE

4. DC MOTOR

5. REED SENSOR

6. PHOTO-SENSOR

7. OPTOCOUPLER

8. APPLICATIONS OF SOLAR SEEKER CELL

9. CONCLUSION

Documents

Solar Seeker (Major Project)